This is a video of the concept "nights" version of Sonic Xtreme for Sega Saturn. Looking to produce a concept for a 3D sonic, a Sega USA team either used or closely follwed the design of "Nights" and caused problems internally at Sega. Thinking or knowing that the US team had used their engine, the Japanese nights team had a fit. The engine was scrapped and a different engine, the so called "fish eye" version was used. This engine was later canceled as unworkable.
This video is from the only copy of the game in existence, which sold for nearly $3000 in 2006.
The music you're hearing is the actual game itself.